Reference Manual

Turbo PMAC/PMAC2 Software Reference

Turbo PMAC Global I-Variables 39

Turbo-PMAC-to-Host Checksum: Turbo PMAC will compute the checksum of any communications

line it sends to the host. This checksum includes control characters sent with the line, including the final

<carriage-return>. The checksum is sent immediately following this <carriage-return>.

On a multiple-line response, one checksum is sent for each line. Note that this checksum is sent before

the checksum of the command line that caused the response.

For more details on checksum, refer to the Writing a Host Communications Program section of the

manual.

Serial character errors: If Turbo PMAC detects a serial character error, it will set a flag so that the

entire command line will be rejected as having a syntax error after the <CR> is sent. With I4=0 or 1, it

will also send a <BELL> character to the host immediately on detecting the character error. Note that this

mode will catch a character error on the <CR> as well, whereas in the I4=2 or 3 mode, the host would

have to catch an error on the <CR> character by the fact that Turbo PMAC would not respond (because it

never saw a <CR>).

I5 PLC Program Control

Range: 0 to 3

Units: None

Default: 1

I5 controls which PLC programs may be enabled. There are two types of PLC programs: the foreground

programs (PLC 0 and PLCC 0), which operate at the end of servo interrupt calculations, with a repetition

rate determined by I8 (PLC 0 and PLCC 0 should be used only for time-critical tasks and should be

short); and the background programs (PLC 1 to PLC 31, PLCC 1 to PLCC 31) which cycle repeatedly in

background as time allows. I5 controls these as follows:

Setting

Meaning

Foreground PLCs off; background PLCs off

Foreground PLCs on; background PLCs off

Foreground PLCs off; background PLCs on

Foreground PLCs on; background PLCs on

Note that an individual PLC program still needs to be enabled to run -- a proper value of I5 merely

permits it to be run. Any PLC program that exists at power-up or reset is enabled automatically (even if

the saved value of I5 does not permit it to run immediately); also, the ENABLE PLC n or ENABLE

PLCC n command enables the specified programs. A PLC program is disabled either by the DISABLE

PLC n or DISABLE PLCC n command, or by the OPEN PLC n command. A CLOSE command

does not re-enable the PLC program automatically – it must be done explicitly.

I6 Error Reporting Mode

Range: 0 to 3

Units: None

Default: 1

I6 controls how Turbo PMAC reports errors in command lines. When I6 is set to 0 or 2, PMAC reports

any error only with a <BELL> character. When I6 is 0, the <BELL> character is given for invalid

commands issued both from the host and from Turbo PMAC programs (using CMD”{command}”).

When I6 is 2, the <BELL> character is given only for invalid commands from the host; there is no response

to invalid commands issued from Turbo PMAC programs. (In no mode is there a response to valid

commands issued from PMAC programs.)